1. Field of the Invention
The present invention is directed to an emulsified lubricant. More specifically, the present invention is directed to a water-in-oil emulsion containing sulfurized. diisobutylene and/or triisobutylene. 2. Background of the Prior Art
The use of water-in-oil emulsion fluids as lubricants in industrial applications, for example, as hydraulic fluids, and in other applications where lubricants are necessitated is well known to those skilled in the-art. An essential aspect of water-in-oil emulsion lubricants is the presence of oil as the continuous phase with water dispersed therein. The continuous oil phase of the lubricant provides the necessary lubricity. At the same time the discontinuous, dispersed water phase contributes fire-resistance. Thus, water-in-oil emulsion lubricant fluids combine lubricating inflammability characteristics.
A major difficulty in utilizing these otherwise excellent hydraulic lubricating fluids is the possibility of loss of stability of the emulsion. In many water-in-oil emulsions of the prior art water particles tended to agglomerate in clusters and to settle to the lower part of the reservoir in which the fluid was maintained. The result of this emulsion breakdown is a continuous oil phase which is obviously non-fire resistant. Not only does such a result eliminate a major requirement of emulsifiable lubricants, fire resistance, but, moreover, such a condition, in which free water is present, can cause corrosion of lines and working parts as well as rapid wear of pump parts due to lack of lubrication. Obviously, therefore, it is essential that water-in-oil the hydraulic fluids maintain their stability over the long period of time in which they are in service.
A major cause of breakdown of emulsifiable lubricants including hydraulic fluids is high temperature. As those skilled in the art are aware, continued exposure to elevated temperatures tends to breakdown water-in-oil emulsion hydraulic fluids.
The problem of maintaining stability of water-in-oil emulsion hydraulic fluids has been addressed in the prior art U.S. Pat. No. 4,483,777 discloses the use of a stabilizing amount of stabilizer selected from the group consisting of water-soluble aminohydroxy compounds and a heterocyclic amine.
Another additive, provided in water-in-oil emulsion fluids, is reported in U.S. Pat. No. 4,225,447 to produce thermally stable emulsions. The emulsion of this patent includes an additive selected from the group consisting of an alkenylsuccinic anhydride having a number average molecular weight of about 300 to 3,000; the alkenylsuccinic anhydride in combination with a rosin salt; and the anhydride in combination with an amine and a rosin soap.
U.S. Pat. No. 3,407,143 provides a water-in-oil emulsion which is reported to have good high temperature stability by the addition thereto of polyethylene.
Several prior art references teach the use of a calcium petroleum sulfonate as an emulsifier. For example, U.S. Pat. Nos. 3,019,190; 3,159,580 and 3,234,143 all make this disclosure. This emulsifier is usually provided in combination with a stabilizer. In the '190 patent a calcium soap of a long chain aliphatic fatty acid is utilized. The '580 patent stabilizer is a potassium salt of a saturated straight-chain fatty acid. Finally, the '143 patent suggests the calcium petroleum sulfonate be used in combination with an alkali metal hydroxide naphthenic acid.
A similar teaching is made in U.S. Pat. No. 3,268,447. The '447 patent discloses an alkali metal or alkaline earth metal sulfonate as a component in a water-in-oil emulsion fire-resistant fluid.
Other similar teachings utilizing calcium sulfonate as the basic emulsifier include U.S. Pat. Nos. 3,080,322 and 3,088,914. These patents combine the sulfonate emulsifier with naphthenic acid salts or soaps of several metals, with calcium being the particularly preferred metal, as the stabilizing medium, to produce fire-resistant water-in-oil emulsions.
U.S. Pat. No. 3,285,851 describes the utilization of a hydrogenated polyisobutylene as the lubricating oil base in a water-in-oil emulsion. This patent reports that hydrogenated polyisobutylene emulsions are more stable than polybutylene emulsions.
The patents described above all advance the water-in-oil emulsion art. Although they all allege improved emulsion stability there still remains a need in this art for improved water-in-oil emulsion stabilizers which provide protection against breaking of the emulsion when the emulsion is exposed to elevated temperatures over long periods of time.